Method of treating material in a vacuum



Aug. 10 1926.

C(MINTON METHOD OF TREATING MATERIAL IN A VACUUM Original Filed March 4. 1920 8) 2 4 ATTORNEY g z ENi ENTOR Patented Aug. 10, 1926.

UNITED "Sr-Ares OGDEN MINTON, 0F GREENWICH, CONNECTICUT.

METHOD OF TREATING IIMIATIERIAL IN A VACUUM:

Original application filed March 4, 1920, Serial No. 363,350. Divided. and this application filed March 20, 1922,'Seria1 No. 545,217.

This application is a division of my copending application Treatment of materialin a vacuum andapparatus, filed March 4, 1920, Ser. No. 363,350, Case F;

The present invention relates to an ap paratus and method for the drying of paper and other material, as sheet material, and immediately coating, or coloring. or sizing or impregnating it while still in the vacuum chamber. I

My improved method consists in passing the material which is to be dried into a vacuum chamber through a liquid sealing medium which has no aflinity for the material, subjecting it. to heat to drive off its contained moisture, immediately coating or coloring, or sizing or impregnating the material while in the vacuum chamber, and then passing the material out of the chamber through a seal. I

This method may be practiced by the use of various forms of apparatus, some of which are herein disclosed. *In any form, however, it is essential thatthe apparatus be provided with a closed chamber in vwhich a partial vacuum may be maintained. In order that the material to be dried and treated may be continuously passed through the vacuum chamber, the latter is provided with openings closed to the admission ofair by a liquid sealing medium which has no affinity for the material. The liquid seal effectively closes theentrance and exit passages against-the admission of air to the chamber, but permits the passage of the material into and-out of the chamber.

My invention furtherrelates to obtaining a better and more uniform product than any now known on the market. "My invention further relates to theamethod of coating or impregnating sheet material which insures that there will be no blemishes, uneven'surfaces, blisters or minute. raised portions" due to the air which maybe held or occluded within the sheet material, which. inthe present practice of coating-as for example with a water-proof compound, leads to rejections or discards due to these imperfections with the consequent waste of material and labor.

My invention further relates to the treatment of paper and drying it in a vacuum chamber, and coating or impregnating or coloring it therein without breaking the vacuum. My invention further relates to performing these steps continuously on a Renewed February 17, 1926.

continuous web of paper. This web of paper may be fed direct from the wet end of a paper machine, or the web may be first wound into a roll or reel as may be found convenient or expedient;

, My invention further relates to manufacother advantages this insures that the paper will have bright colors, which will be substantially uniform in different runs of paper, permitting matching of colored paper without any appreciable difference in tone or color. i

My invention further relates to rapidly and expeditiously coating "or impregnating sheet material in a continuous web or sheet. My invention further relates to sizing paper in a vacuum chamber at such low temperatures as not to injure the fibers of the aper or the size. My invention further reates to withdrawing the occluded air from the paper and immediately drying and then filling the interstices normally filled with the occluded air with the size. My invention further relates to carrying out this method continuously with a continuous web of paper which passes'into and out of the vacuum .chamber without breaking the vacuum. I

More practically my present invention relates 'to passing material into a Vacuum chamber, without breaking the vacuum, drying it in the vacuum chamber while under little or no substantial tension, so that the constituent elements, as for example, the fibers of paper, will not be substantially changed from the position assumed by them on the wire of the paper making machine. Then immediately coating, coloring, sizing or impregnating the material while still. in the vacuum chamber, and then continuously passing the coated, impregnated, sized or colored material out of the vacuum chamber without breaking the vacuum. v

My invention further relates to certain steps, and combinations of steps, also to certain elements and combinations of elements, whereby the method or processes herein described may be carried out, as well as to certain details of construction, all of whichnumerals refer to similar parts in the several figures.

Fig; 1 is a vertical diagrammatic section of one form of apparatus, which may be used to carry out my improved method;

Fig. 2 is a vertical diagrammatic section of a modification in which the sheet material is heated by one or more electric heaters. In describing my invention I will describe it as applied to sheet material in the form of paper though it is to be distinctly understood that textile fabrics may also be treated by my process and that my broader claims cover all forms of materials.

In the ordinary drying of a web of paper such high heat is used as to injuriously affect the fibers of the paper; and in case the paper is colored it will materially affect the coloring matter and mordants' used. Drying paper in the high temperatures used in ordinary practice often affects the size so that the resulting paper varies in quality, is not uniform and is not a perfect product.

In coating or impregnating fabrics it is found in practice that the coated fabric will frequently have blemishesdue to large. or' small blisters and'blow holes, these often be- 'the sheet material which will permit the coating or"impregnating material, "whatever it may be, to thoroughly fill these minute interstices or pockets normally occupied by occluded air, forming thereby a better and more uniform product and one devoid of blisters, blow holes or such blemishes.

The web 1 of paper may be fed direct from the wet end of a paper machine, the vacuum chamber A being properly positioned adjacent to such paper machine. Or, the web 1 may be fed, from a roll or reel 3 of Wet or damp paper over the guide roller l and into the liquid seal 5. This seal may be of any suitable medium which has no aflinity for or deleterious effect upon the sheet material treated. I preferably use a liquid seal of 1,cas,4.eo

mercury, though it is to be distinctly understood, that any amalgam, alloy, or any other suitable liquid sealing medium may be employed which has the characteristics above specified. The web'l is fed down through this liquid seal under the roller 6 and then u into the vacuum chamber 2 in contact with the guide roller 7. The material is then fed through the vacuum chamber under just sufficient pull or tension to insure its passage and without substantially causing the con stituent elements of the material to rearrange themselves.

In the ordinary commercial paper making machine the fibers of the paper stock or furnish are formed on the wire of the machine. There they are interlaced and locked, more or less, firmly together. Taking the wet web from the wire of the paper machine and running it over a series of heated drying drums or cylinders tends to pull the fibers in the direction of travel of the heated rollers, cyl inders or driers as they .are technically known. The more pull on the wet web, the more the fibers tend to straighten out in the direction of travel of the heated cylinder or drier which is drying the web and moving at high speed. Each succeeding drier tends to augment this pulling of the fibers or the paper.

This not only results in the web shrinking crosswise but materially affects the strength of the resulting paper.

. By drying the web so that there is little or no tension upon it permits the fibers to dry at random or at will. That is, substantially as they were interlaced together on the wire of the paper machine.

This results in the sheet being as strong lengthwise of the sheet as it is crosswise of the sheet. This is not true where considerable tension has been placed on the wet web by passing over large drying drums or cylinders. It is, therefore, obvious that by my method a new result is accomplished. A coated, colored, sized or impregnated paper of a given strength is obtained with relatively poor stock or furnish. To obtain a. coated, colored, sized or impregnated paper of the same strength made "by a method in" which the fibers of the paper were not permitted to dry at random or at will. or substantially as formed on the wire of the paper machine, would require much better and more expensive stock or furnish.

Various means may be used to feed the material through the vacuum chamber and still come within the terms of my invention, as previously explained.

I have shown the material, as for example a web of paper passing through the vacuum chamber A in folds or loops, passing under the guide rolls 8-8, and over the guide rolls 99. Preferably I beat the material as it passes through the vacuum chamber, but in a manner which will not cause the fibers to be substantially weakened or pulled out in the The vacuum chamber is provided with pipes 19, 19 leading to any suitable form of vacuum apparatus. I also preferably provide the vacuum chamber with windows 20, so that the operator can at all times see into the interior of the vacuum chamber. The chamber 22, in which the bath 12 is located, can be drained by the cock 21. Additional liquid can also besupplied to the bath 12 by the same cock. In some cases, the coating, coloring, impre nating or sizing bath 12 may be heated 1n any suitable manner as for example by the steam pipes 23.

The apparatus shown in Fig. 2 is the same as in Fig. 1, except instead of steam or hot water radiators 10, 10, I use electric heaters 24, 24. a 1

Thebath 12 may be any material which it is desired to coat-or impregnate or size the web 1. wax, tar or in fact any coating or waterproofing impregnating or coloring material.

The web 1 passing into'said coating or impregnating bath 12 dry, and with its intorstices devoid of practically all occluded air will immediately become coated or impregnated with portions of said bath as it passes under the submerging rollers 13 and out between the squeeze rollers 14, 14. which remove all the surplus-coating or impregnating material. Tlie amount of the coating or impregnating material taken up by the web 1 will depend somewhat upon the speed with which the web is fedthrough the vacuum chamber, but it is to be under-' stoodthat my machine is a high speed machine. The web will then pass over the guide rollers 15, 15 and down into the second liquid seal 5 under the roller 16. This liquid seal 5 is preferably of the same material as the first liquid seal 5, though of course it need not necessarily be, but it must not have any affinity for or deleterious ac-' tion upon the coated or impregnated web 1. The web is then fed over the guide roller 17 and is preferably rolled in the roll or reel 18, though it may be cut or stacked or further treated. as may be found convenient or expedient.v

The thermal efficiency of my vacuum method is very much greater than that of the atmospheric cylinder drying heretofore in universal use for drying paper. Theoretically, it requires about 5287 pounds of which a higher grade furnish is used. making newsprint paper, I am able to dis- For example, it may be size,

steam to dry one ton of paper at atmospheric pressure, but to compensate for convection and conduction losses, and those due to leaks in the piping system, and other inefficiencies, it has been shown in practice that about 10,600 pounds are required.

In my method, using a vacuum of about 28", th convection, conduction and piping losses are exceedingly small and the total steam required to dry a ton of paper by my method is approximately 5200 pounds.

It is an established fact that paper dried at low temperatures is much stronger than when it is dried at the high temperatures used in paper machine atmospheric drying. Paper dried in a vacuum of 28", or at a temperature of about 100 F., as irr my method, is very much stronger than paper dried at atmospheric pressure, when the steam in the. driers is at 228 F. When paper is dried by my method, therefore, a cheaper furnish can be used and still produce a coated or sized paper equal in strength to. atmospheric dried paper, Iin

pense with a. considerable portion 7 of the more expensive sulphite pulp, as this can be replaced withthe cheaper ground wood pulp. By my method I also reduce the number of breaks in the web as it passes over the cylinder. Nor will the size or coloring matter and mordants, of any be used be injuriously affected.

Furthermore, in my method there is a great saving of heat (or steam) because the process is carried on in a Vacuum chamber which acts on the principle of a thermos bottle, and the steam and vapors driven out of the wet paper are caught 1n the closed vacuum chamber, and conducted'away to the condenser. The operating room is free from steam, humidity and heat, and fans, and exhausters are dispensed with. In the use-of my method the apparatus is at all times operating under definite humidity, the control of the drying can be closely standardized, and the moisture content inithe paper carefully regulated. y

Having pointed out the many advantages of my method and apparatus over those heretofore used, it will be apparent that the use of my invention results in great economy in the initial cost of apparatus and in large savings in cost of operation, maintenance and repairs.

Having thus described this invention .in connection with illustrative embodiments thereof, to the details of-which I do not her without breaking the vacuum, drying it in the vacuum chamber by passing it through the vacuum chamber with little or no tension which will permit the constituent elements of the material to dry at Will or a random, then coating or impregnating the material in the vacuum chamber, and passing the coated or impregnated material out of the vacuum chamber without breakin the vacuum.

2. The method of treating a web of Wet paper consisting in continuously feeding it into a vacuum chamber without breaking the vacuum, drying it in the vacuum chamber I under little or no tension so as not to cause the fibers to substantially rearrange themselves from the position assumed by them on the wire of the paper machine, then While still in the vacuum chamber continuously coating, sizing, coloring or impregnating the web, and continuously withdrawing it from the vacuum chamber without breaking the vacuum.

The method of treating a web of wet paper consisting in feeding it continuously into a vacuum chamber through a liquid seal that has no deleterious effect upon' said web, continuously drying the web in the vacuum chamber, under little or no tension so that its fibers will dry while under little or no tension, continuously coating or impregnating the web in the vacuum chamber, and continuously Withdrawing it from the vacuum chamber through a liquid seal that has no afinity for or -deleterious efiect upon said coated or impregnated web of paper.

OGDEN MINTON. 

